Nitric is nice to have, but many times there are ways to recover values and process them by other means, silver is one that is more difficult without using nitric acid, so as much as possible you should study the other methods.
Take processing a gold silver 14K ring for example; normally you would inquarter with silver, shot, and use nitric to part gold from silver. but you could also use gold to bring the 14k ring up to about 22kor more in a melt, shot, hammer flat and then dissolve gold from silver, using HCl/bleach or HCl/peroxide method, yes you would need gold in the process, and that would tie up values, another Idea that may work is alloy with copper not mixing melt very well pour shot and use the concentrated sulfuric cell?
I do not live in Canada or other country's where nitric is almost impossible to get, I can buy potassium nitrate locally, or have sodium nitrate shipped from mail order, I can buy very high priced nitric in tiny bottles at mining store, or drive 250 miles for a nitric at Action mining in sandy Oregon, although I would probably be able to buy nitric easier and cheaper if I got a business license and was able to purchase from large chemical house like Univar at very decent prices, but then I would be shifting from a back yard hobby to a more regulated area if you understand what I am saying here, and for now I like doing this as a small scale hobby,
What are the regulations on fertilizers in your country? Here it seems to be more difficult to find the more pure nitrates locally, what are regulations if you come across border and buy fertilizer? Or buy from shipping dealers on a web site?
Noxx lives in Canada and he was able to get the supplies he needed, I thought one time he had a member ship him some fertilizer, I could be wrong, but he now is working as a business, and I would guess he is using nitric acid; maybe he will read this and add his thoughts.
As many members from Canada (or other country's) as we have maybe the members from those country's could pool their Knowledge of where or how to get or do work a rounds, or even purchase needed supply's members helping each other with the problem?
I guess I should have not been so wordy and just said where there is a will there may be a way? Just do not give up.